Constraints for the latest glacial advance on Wrangel Island, Arctic Ocean, from rock surface exposure dating

During an expedition to Wrangel Island in 1997, three samples of quartz veins were collected for surface exposure dating. Two were bedrock surface samples from different parts of the island, one was from a local boulder. The samples were collected where former coverage by valley glaciers can be excluded. Especially, the bedrock surface samples were expected to provide new constraints for the chronology of glaciations on the island and on the arctic continental shelf in the Beringian region. Minimum exposure age estimates for these bedrock samples, calculated on the basis of 10Be concentrations, are 64,600±6400 and 26,400±2100 years. These estimates suggest that no major glaciations have affected Wrangel Island or the adjacent shelf area after 64,600±6400 years. Specifically, these dates seem to rule out any major glaciation during the Last Glacial Maximum (LGM). The estimates should however be regarded as preliminary, as only two bedrock surface samples were analysed, but are compatible with the absence of glacial morphology and sediments, and with radiocarbon dates from mammoth remains.